The present invention relates to ring structure 1:N duplex communication equipment in which a host device and a plurality of slave devices are interconnected in a ring form in two ways, and more particularly to 1:N duplex communication equipment for transmitting data from a specified slave device in response to multi-address data which has been sent from the host device.
Referring to FIG. 2, there is shown 1:N duplex communication equipment, which has conventionally been used. Paths 1 to n respectively interconnect a host device 21 and a plurality of slave devices 22-1 to 22-n.
The host device 21 includes a path distributing part 23 for distributing the plurality of paths 1 to n, a plurality of path selecting parts 25-1 to 25-n for selecting paths from the slave devices 22-1 to 22-n of two-way transmission lines and a received data selecting part 26 for selecting effective received data upon receiving data from the selected plurality of paths. These parts are arranged for transmitting multi-address data to the plurality of slave devices 22-1 to 22-n. The plurality of slave devices 22-1 to 22-n include path selecting parts 27-1 to 27-n for selecting paths from the two-way transmission lines and path transmitting parts 24-1 to 24-n for distributing received data to the paths of the two-way transmission lines.
The host device 21 transmits data having identical information through the plurality of paths 1 to n. The slave devices receive the data transmitted from the host device through the paths selected by the path selecting parts 27-1 to 27-n. When there is data to be transmitted, each of the slave devices 22-1 to 22-n transmits a data effective signal together with the data to be transmitted through the path. The paths from the slave devices 22-1 to 22-n are respectively distributed to the two-way transmission lines in the path transmitting parts 24-1 to 24-n.
In the host device, the paths 1 to n from the two-way transmission lines are respectively selected by the path selecting parts 25-1 to 25-n and received data is selected from the selected path by the received data selecting part. The host device 21 and the path selecting parts 27-1 to 27-n of the slave devices 22-1 to 22-n operate so as to select a normal transmission line when one transmission line fails.
The conventional 1:N duplex communication equipment described above with reference to FIG. 2 is disadvantageous in that the same number of paths as that of slave devices is needed.